The invention pertains to a method for determining the rotational position of the rotor of an electric machine comprising star-connected phase conductors, wherein a measurement signal (M) representative of the rotational position of the rotor within a magnetic half-period is acquired.
A method of this type is known from EP 1 005 716 B1. According to this known method, the rotational position of the rotor is determined on the basis of the dependence of the inductances of the phase conductors on the position of the rotor; this is possible because the inductances vary with the changing degrees of saturation of the pole winding cores and the changing geometric influences of the rotor's rotational position. Within a magnetic half-period, there is therefore a unique relationship between the inductances of the phase conductors and the rotor's rotational position. Acquiring a measurement signal (M) representative of the inductance of one or more phase conductors and thus of the rotor's rotational position can be made more difficult, however, by inductive couplings between the phase conductors.